Technical problems interfering with Parisian mass transportation are rare,
albeit not as rare as they used to be. The real problem is continual labor
strikes that cripple all or part of the system on a regular basis—they are
one reason why Paris lost its bid for the Olympics in 2012.
Mass-transit workers are among the most strike-prone workers in France,
even though their employment conditions are extremely generous by the
standards of many other industries. They will strike for the most trivial ofreasons, often with very little advance notice, and sometimes for extended
periods. Most strikes, however, last only a day, and affect only certain
Métro lines. The affected lines may stop completely or simply run trains
much more slowly. The bus network is rarely affected.
Strikes at the SNCF may affect commuter trains or parts of the RER, but
these are somewhat less frequent than RATP strikes.
In some seasons, there may be transit strikes roughly once a week, so be
prepared. It won’t generally prevent you from getting around, but it may
slow you down or make use of the Métro impractical. You’ll know there’s
a strike when you arrive on a platform and see ten times the normal
number of people waiting for a train. Public announcements are usually
made as well (on video displays, and audibly).